Signal control apparatus

ABSTRACT

An object of the present invention is to improve reliability after the control of a microcomputer recovers. A signal control apparatus according to the present invention includes a microcomputer, an output control unit that receives a reset signal and a load control signal from the microcomputer and outputs a load output signal to a load, and when the output control unit receives the reset signal, the output control unit maintains a state of the load output signal immediately before the reset signal is received, and when the load control signal is switched, the output control unit releases the maintaining state of the load output signal.

TECHNICAL FIELD

The present invention relates to a signal control circuit, and more particularly to a signal control apparatus used in a power conversion device that controls a rotating electric machine that generates driving force of a vehicle.

BACKGROUND ART

An electric control apparatus includes a microcomputer (main microcomputer 20 in PTL 1) and an output control unit (sub microcomputer 30 and latch circuit 40 in PTL 1) and controls a load output signal (relay 50 in PTL 1).

In a case where there is an abnormality in the microcomputer, the microcomputer is reset by a reset signal (RESET 11 in PTL 1). During the period, a state of the load output signal is maintained by the output control unit.

PTL 1 aims to prevent a failure due to continuous ON/OFF of the load output signal (relay 50).

However, it has been insufficient to secure reliability after the control of the microcomputer 100 recovers from the time of various abnormalities.

CITATION LIST Patent Literature

PTL 1: JP 2008-223692 A

SUMMARY OF INVENTION Technical Problem

An object of the present invention is to improve reliability after the control of a microcomputer recovers.

Solution to Problem

A signal control apparatus according to the present invention includes a microcomputer, an output control unit that receives a reset signal and a load control signal from the microcomputer and outputs a load output signal to a load, and when the output control unit receives the reset signal, the output control unit maintains a state of the load output signal immediately before the reset signal is received, and when the load control signal is switched, the output control unit releases the maintaining state of the load output signal.

Advantageous Effects of Invention

According to the present invention, it is possible to improve the reliability after the control of the microcomputer recovers.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block configuration diagram of a motor control circuit and a gate control circuit 2 according to the present embodiment.

FIG. 2 is a block configuration diagram of an output control unit 200.

FIG. 3 is a timing chart of each signal illustrated in FIG. 1.

FIG. 4 is a table illustrating a state corresponding to each timing in FIG. 3.

FIG. 5 is a block configuration diagram of a motor control circuit and a gate control circuit 2 according to a second embodiment.

FIG. 6 is a block configuration diagram of a motor control circuit and a gate control circuit 2 according to a third embodiment.

FIG. 7 is a block configuration diagram of a motor control circuit and a gate control circuit 2 according to a fourth embodiment.

DESCRIPTION OF EMBODIMENTS

Embodiments according to the present invention will be described with reference to FIG. 1 or figures.

First Embodiment

FIG. 1 is a block configuration diagram of a motor control circuit and a gate control circuit 2 according to the present embodiment.

The motor control circuit 1 according to the present embodiment includes a battery power supply 10, an ignition switch 20, a ground line 30 connected to the battery power supply 10, a transistor 50 controlled by a load output signal 210, a microcomputer 100 that outputs a motor control signal 120 that is a pulse width modulation (PWM) signal for converting a direct current power supply into an alternating-current signal, a reset signal 130, and a load control signal 110, a output control unit 200 that outputs the load output signal 210, a load 300 controlled by the transistor 50, and a reset control unit 400 incorporated in the microcomputer 100.

The gate control circuit 2 includes a gate drive unit 500, an insulated gate bipolar transistor (IGBT) control signal 510, an IGBT 600, and a high voltage battery 700.

The microcomputer 100 controls the load control signal 110 and the motor control signal 120.

For example, a main function is to control a motor 800 by the motor control signal 120 via the gate drive unit 500 and the IGBT 600.

The load control signal 110 is a signal for switching the load 300 to ON or OFF when the microcomputer 100 is not in a reset period and in an initialization period. For example, when the voltage is 5 V, the load 300 is turned on, and when the voltage is 0 V, the load 300 is turned off.

The motor control signal 120 is a signal that controls a U-phase of the motor 800, a signal that controls a V-phase and a signal that controls a W-phase.

The output control unit 200 outputs the load output signal 210 in accordance with the reset signal 130 and the load control signal 110. The load output signal 210 turns on or off the load 300 by turning on or off the transistor 50.

The load 300 is subjected to ON/OFF control by the load output signal 210 from the output control unit 200. For example, the load 300 controls ON/OFF of a power supply of the gate drive unit 500 in accordance with the load output signal 210. In the present embodiment, the load 300 is a power supply unit of the gate drive unit 500.

The reset control unit 400 controls the reset signal 130 and includes, for example, a power supply integrated circuit (IC). The reset control unit 400 monitors a state of the battery power supply 10 via the ignition switch 20 and issues the reset signal 130 when the voltage decreases.

The reset signal 130 issues a reset in a case where there is an abnormality in the control of the microcomputer 100. The reset signal 130 is notified to the microcomputer 100 and the output control unit 200. As for the reset signal 130, High represents a normal state and Low represents a reset state.

The gate drive unit 500 drives the motor 800 by controlling the IGBT 600 by the IGBT control signal 510 in accordance with the motor control signal 120 from the microcomputer 100. The IGBT control signal 510 is a signal that controls the IGBT 600 to be ON and OFF and includes a total of six signals of a U-phase upper arm, a U-phase lower arm, a V-phase upper arm, a V-phase lower arm, a W-phase upper arm, and a W-phase lower arm in order to control the motor 800.

The IGBT 600 is a switch for passing a current to the motor 800 and is controlled by the IGBT control signal 510.

The high voltage battery 700 is a power supply for driving the motor 800. The motor 800 is a motor for driving a vehicle.

The battery power supply 10 supplies a power supply to the microcomputer 100 and the reset control unit 400 via the ignition switch 20. The battery power supply 10 includes, for example, a 12 V lead battery mounted on the vehicle. The battery power supply 10 supplies a power supply to the load 300.

The ignition switch 20 shuts off the supply of the battery power supply 10 to the microcomputer 100 and the reset control unit 400. The ignition switch 20 includes, for example, a key switch of the vehicle and is turned on when the vehicle is started up and turned off when the vehicle is stopped.

A gatedrive power supply line 40 is a control power supply line to the gate drive unit 500. The transistor 50 turns on and off the load 300 by the load output signal 210.

FIG. 2 is a block configuration diagram of the output control unit 200.

The output control unit 200 includes a pull-up resistor 201, a NOT element 202, an AND element 203, a flip-flop 204, an OR element 205, a pull-down resistor 206, a reset input terminal 207, a load control signal input terminal 208, and a load output signal terminal 209.

The pull-up resistor 201 sets an initial value of the reset signal 130 input to the reset input terminal 207 to High.

The Not element 202 inverts the reset signal 130 input to the reset input terminal 207.

The AND element 203 outputs a state of the load output signal 210 output to the load output signal terminal 209 when the reset signal 130 input to the reset input terminal 207 is Low.

The flip-flop 204 outputs an output signal of the AND element 203 at the fall timing of the load control signal 110 input to the load control signal input terminal 208.

The OR element 205 subjects the output signal of the flip-flop 204 and the load control signal 110 input to the load control signal input terminal 208 to OR.

A pull-down resistor 206 sets an initial value of the load control signal 110 input to the load control signal input terminal 208 to Low.

FIG. 3 is a timing chart of each signal illustrated in FIG. 1.

(1) Ignition illustrates a state of the ignition switch 20. The example of FIG. 3 illustrates that the ignition switch 20 is ON at High and the ignition switch 20 is OFF at Low.

(2) Load control signal 110 illustrates a state of the load control signal 110.

(3) Reset signal 130 illustrates a state of the reset signal 130. The example of FIG. 3 illustrates a normal state at High and a reset state at Low.

(4) Load output signal 210 illustrates a state of the load output signal 210. The example of FIG. 3 illustrates that the load is ON at High and the load is OFF at Low.

Timing 1001 illustrates a start timing of the vehicle. At timing 1002, when the load control signal 110 is switched to ON, the load output signal 210 changes from a state of maintaining an immediately preceding state to an ON state.

Timing 1003 illustrates that when the reset state is entered, that is, when the reset signal 130 turns to Low, the load output signal 210 maintains the immediately preceding state. The timing 1003 illustrates a state in which the output of the microcomputer 100 becomes unstable, but the load control signal 110 turns to OFF by the pull-down resistor 206.

Timing 1004 illustrates a state in which the load output signal 210 maintains the previous state when reset is released, that is, when the reset signal 130 turns to High. The timing 1004 illustrates a state in which the output of the microcomputer 100 becomes unstable because the output is being initialized but the load control signal 110 turns to OFF by the pull-down resistor 206.

Timing 1005 illustrates a state in which since the load control signal 110 turns to ON after the output of the microcomputer 100 is initialized, the load output signal 210 turns to ON.

At timing 1006, when the load control signal 110 is switched to OFF, the load output signal 210 changes from the state of maintaining the immediately preceding state to an OFF state.

At timing 1007, when the reset state is entered, that is, when the reset signal 130 turns to Low, the load output signal 210 maintains the immediately preceding state. The timing 1007 illustrates a state in which the output of the microcomputer 100 becomes unstable, but the load control signal 110 turns to OFF by the pull-down resistor 206.

At timing 1008, when the reset is released, that is, when the reset signal 130 turns to High, the load output signal 210 maintains the immediately preceding state.

At timing 1009, when the load control signal 110 is switched to ON, the load output signal 210 changes from the state of maintaining the immediately preceding state to a state of turning to ON.

FIG. 4 is a table illustrating a state corresponding to each timing in FIG. 3.

In a normal state 2001, when the reset signal is High and the load control signal input terminal is ON, the load output signal turns to ON. The normal state 2001 illustrates a state from the timing 1002 to 1003 in FIG. 3 and a state from the timing 1005 to 1006.

In a reset state 2002, when the reset signal turns to Low, an immediately preceding state of the load output signal is maintained. The reset state 2002 illustrates the state from the timing 1003 to 1004 in FIG. 3.

In an initial processing state 2003, since timing at which the maintaining state of the load output signal is released is when the load control signal is switched, the reset signal turns to High, but the immediately preceding state of the load output signal is maintained. The initial processing state 2003 illustrates a state from the timing 1004 to 1005 in FIG. 3.

In a normal state 2011, when the reset signal is High and the load control signal input terminal is OFF, the load output signal turns to OFF. The normal state 2011 illustrates a state from the timing 1001 to 1002 in FIG. 3 and the state from the timing 1006 to 1007.

In a reset state 2012, the immediately preceding state of the load output signal is maintained when the reset signal turns to Low. The reset state 2012 illustrates a state from the timing 1007 to 1008 in FIG. 3

In an initial processing state 2013, since timing at which the maintaining state of the load output signal is released is when the load control signal is switched, the reset signal turns to High, but the immediately preceding state of the load output signal is maintained. The initial processing state 2013 illustrates a state from the timing 1008 to 1009 in FIG. 3.

Since the microcomputer 100 cannot control the load output signal 210 in the reset state, the state of the load output signal 210 immediately before the reset signal 130 is received, and after the control of the microcomputer 100 recovers, that is, after the load control signal 110 is switched, the maintaining state of the load output signal 210 is released.

Therefore, even after the control of the microcomputer 100 recovers, the load 300 by the load output signal 210 can be continuously controlled.

Second Embodiment

FIG. 5 is a block configuration diagram of a motor control circuit and a gate control circuit 2 according to a second embodiment. A difference from the first embodiment is that a reset control unit 400 is configured to be separated from a microcomputer 100 and receives supply of power from a battery power supply 10 that is the power supply of the microcomputer 100.

The reset control unit 400 controls a second reset signal 410. The reset control unit 400 includes, for example, a power supply IC and monitors a state of the battery power supply 10 via an ignition switch 20 and transmits the second reset signal 410 when a voltage decreases.

As a result, by monitoring a power supply voltage of the microcomputer 100, it is diagnosed whether the control of a load control signal 110 is correct. For example, in a case where the power supply voltage decreases, since the microcomputer 100 includes a logic circuit, a threshold specification of the logic circuit cannot be satisfied. That is, the load control signal 110 cannot be correctly controlled.

In addition, in the present embodiment, by separating power supplies of the microcomputer 100 and an output control unit 200, it is possible to maintain a mode at the output control unit 200 while the power supply voltage of the microcomputer 100 is decreasing and to continue a process even after recovery. Therefore, abnormal control of a load caused by a decrease the power supply voltage or the like is prevented. A user can avoid stopping the control at an unintended timing.

Third Embodiment

FIG. 6 is a block configuration diagram of a motor control circuit and a gate control circuit 2 according to the third embodiment. A difference from the second embodiment is that a microcomputer 100 includes a first control unit 101 and a second control unit 102.

The first control unit 101 controls a motor control signal 120. The second control unit 102 controls a load control signal 110.

A monitoring signal 420 periodically communicates with the first control unit 101 of the microcomputer 100 and monitors an abnormality of the first control unit 101. For example, the monitoring signal 420 causes the microcomputer 100 to calculate an example and in a case where an answer is incorrect, a second reset signal 410 is transmitted. There is general-purpose serial peripheral interface (SPI) serial communication or the like.

As a result, in a case where there is an abnormality in the first control unit 101 that controls the motor control signal 120 of the microcomputer 100, a reset control unit 400 monitors the first control unit 101 with the monitoring signal 420, thereby being able to suppress runaway of a motor 800 controlled by the motor control signal 120.

In addition, even after the control of the microcomputer 100 illustrated in the first embodiment or the second embodiment recovers, a load 300 by a load output signal 210 can be continuously controlled.

Therefore, after stopping the runaway of the microcomputer 100, it is possible to continue the motor control process even after the recovery and as a result, reliability improves.

Fourth Embodiment

FIG. 7 is a block configuration diagram of a motor control circuit and a gate control circuit 2 according to a fourth embodiment.

A contactor 750 shuts off connection with a high voltage battery 700. For example, in a case where an abnormal current flows in a motor 800, the contactor 750 is shut off by the control of a microcomputer 100.

A smoothing capacitor 751 is a smoothing circuit for converting a PWM signal that controls a motor into an alternating current.

A discharge resistor 752 is a resistor for removing the residual charge of the smoothing capacitor 751. A discharge switch 753 is turned on when the contactor 750 is OFF. In addition, the discharge switch 753 turns to OFF when the contactor 750 is ON.

A NOT element 754 inverts the control of the contactor 750 to control the discharge switch 753. A contactor control signal 310 is controlled by a load output signal 210.

The smoothing capacitor 751 plays an important role in converting a direct current into an alternating current. However, it is necessary to remove the residual electric charge accumulated in the smoothing capacitor 751 except during traveling such as when the motor is stopped or at the time of an abnormality.

A control circuit in a case where there is an abnormality in the gate control circuit 2 includes the contactor 750, the discharge resistor 752, the discharge switch 753, and the NOT element 754. In a case where there is an abnormality in the gate control circuit 2, by simultaneously turning off the contactor 750 and turning on the discharge switch 753, the electric charge accumulated in the smoothing capacitor 751 is discharged, and the circuit is released from a state in which a high voltage is applied.

In other words, since the control by the load output signal 210 in the microcomputer 100 can be continued, the residual charge remaining in the smoothing capacitor 751 can be removed and more safe control can be performed.

In addition, the output control unit 200 has a function of counting a reset signal 130 and turns off the load output signal 210 in a case where there is a count of a predetermined value on the basis of this count function.

In a case where an abnormality of the microcomputer 100 occurs a plurality of times and recovery cannot be achieved, by turning off the load output signal 210 to shut off a circuit, it is possible to further improve the reliability.

REFERENCE SIGNS LIST

-   1 motor control circuit -   2 gate control circuit -   10 battery power supply -   20 Ignition switch -   30 grand line -   40 gatedrive power supply line -   50 transistor -   100 microcomputer -   101 first control unit -   102 second control unit -   110 load control signal -   120 motor control signal -   130 reset signal -   200 output control unit -   201 pull-up resistor -   202 NOT element -   203 AND element -   204 flip-flop -   205 OR element -   206 pull-down resistor -   207 reset input terminal -   208 load control signal input terminal -   209 load output signal terminal -   210 load output signal -   300 load -   400 reset control unit -   410 second reset signal -   420 monitoring signal -   500 gate drive unit -   510 IGBT control signal -   600 IGBT -   700 high voltage battery -   750 contactor -   751 smoothing capacitor -   752 discharge resistor -   753 discharge switch -   754 NOT element -   800 motor -   1001 timing -   1002 timing -   1003 timing -   1004 timing -   1005 timing -   1006 timing -   1007 timing -   1008 timing -   1009 timing 

1. A signal control apparatus comprising: a microcomputer; and an output control unit that receives a reset signal and a load control signal from the microcomputer and outputs a load output signal to a load, wherein when the output control unit receives the reset signal, the output control unit maintains a state of the load output signal immediately before the reset signal is received, and when the load control signal is switched, the output control unit releases a maintaining state of the load output signal.
 2. The signal control apparatus according to claim 1, further comprising a reset control unit that monitors a power supply unit that supplies power to the microcomputer, wherein the reset control unit transmits a second reset signal output to the microcomputer when there is an abnormality in the power supply unit.
 3. The signal control apparatus according to claim 2, wherein the microcomputer includes a first control unit that controls a motor control signal and a second control unit that controls the load, and the reset control unit transmits the second reset signal to the first control unit when there is an abnormality in the microcomputer by a monitoring signal that communicates with the microcomputer and monitors an abnormality.
 4. The signal control apparatus according to claim 1, wherein the load controls a contactor that controls supply and shut-off of power between a motor and a high voltage battery.
 5. The signal control apparatus according to claim 4, wherein the output control unit counts a number of times that the reset signal is transmitted and, in a case where there is a count equal to or larger than a predetermined value, the output control unit turns off the load output signal. 